Databases in depth: what one server does inside

Single-node database internals for system design: pages, the buffer pool and the write-ahead log, group commit, B-trees vs LSM-trees and their amplification, why the primary key decides the working set, clustered vs heap tables, composite and covering indexes, reading EXPLAIN, lost updates and write skew, PostgreSQL vs InnoDB isolation, MVCC with vacuum and purge, pessimistic and optimistic locking, choosing a store, and generating IDs.